If I had to hazard a guess, I would assume it had something to do with the fact that in 5 man content, tanks and healers are each 20% of the group, while in raids, tanks can be as low as 5% (main and off tank) and healers can be much higher.
If I had to hazard a guess, I would assume it had something to do with the fact that in 5 man content, tanks and healers are each 20% of the group, while in raids, tanks can be as low as 5% (main and off tank) and healers can be much higher.